Reclosable paperboard containers, commonly called "flip-top" cartons, are well known in the art, and are widely employed for the packaging of a variety of food products. As shown in the U.S. Pat. No. Re. 26,471, certain of such cartons are provided with a locking reclosure feature, wherein parts of tabs disposed at the front of the receptacle and cover portions of the carton are brought into engagement with one another upon reclosure. The tabs from which the locking parts are produced exist in the unopened carton as unitary elements, which are divided by lines of weakness formed thereacross. In the course of opening the carton, the lines of weakness are ruptured, the rupture being accomplished effectively through a toggle-like action which is produced in the locking tabs.
Characteristic of the prior art cartons of this sort is the location of the severable locking tabs behind a continuous short skirt, which depends from the cover top panel and extends entirely across the carton; the skirt provides the handle by which opening is effected. Since it remains intact after opening, the skirt hides the locking tabs, thereby hampering visual inspection of the conditions of the container for the purpose of determining whether or not it has been tampered with.
To combat that problem, it is proposed to provide a removable section in the outermost layer of the cover skirt, which will be torn away by any attempt to open the package, thus providing clear evidence of tampering. This requires, of course, that the removable section be secured to the receptable portion of the carton, so that it will be displaced by opening. While such securement is desirable not only from the standpoint of affording tamper resistance, but also to minimize the outward bowing of the skirt which as would otherwise tend to occur, it also inhibits the desirable toggle action of any locking tab disposed thereunder. Such toggle action is further inhibited when the contents of the carton are solid (as in the case of ice cream) since virtually no movement thereinto is possible.
In accordance with the instant invention, it was found that locating the locking tabs at the sides rather than the front of the carton enables the incorporation of a tamperproof feature, without inhibiting the toggle action which facilitates opening. However, unless special measures are taken, doing so would entail the presence of an excessive number of material plies at the upper front corners of the package. Not only would too many plies create a high level of stress at those corner locations, causing a tendency for intolerable cracking to occur in the outermost ply of material, but also an excessive number of plies causes undesirable bowing of the cover skirt.
Accordingly, it is an object of the present invention to provide a novel paperboard carton having a locking reclosure feature, and to provide the blank from which it may be produced.
It is also an object of the invention to provide such a carton and blank in which a tamperproof feature is provided.
Another object of the invention is to provide a carton and blank having the foregoing features and advantages, wherein the tendency for bowing and for cracking of the paperboard in the skirt corner areas is minimized.
A further object is to provide such a blank which is especially adapted for convenient glueing and setting-up on conventional machinery, utilizing a minimum number of operations.
Still another object is to provide a carton of the foregoing sort which is especially suited for the packaging of hard products, such as ice cream.